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| Help me understand cav plate adjustments.... http://mudmotortalk.com/mmt_v2/viewtopic.php?f=6&t=4825 |
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| Author: | cbrdux [ Wed Sep 23, 2009 8:23 pm ] |
| Post subject: | Help me understand cav plate adjustments.... |
OK..so here's the setup.. PolarKraft 1650 jon boat, short transom 16" 27hp Kawi Mudbuddy Longtail...TALL TRANSOM Boat jumps quickly to plane. Runs 14.6 mph Low idle at 1200 rpms WOT rpms out of water @4150 WOT in water @3950 (deep water) Motor runs strong and pushes the boat straight...BUT................. The prop wants to jump out of the water and the motor handle is driven towards the floor. I cannot stand straight up to run the motor. I have to hunch over in order to keep the prop in the water and where it wants to run...It seems that the props wants to run a little deep, I can push down on the handle to get the prop half in/ half out of the water and speed jumps to 15.4. Am I thinking correctly here..is it an adjustment on the cav plate, or is it an issue with the angle of running a tall transom motor on a short transom boat? The hole shot is good, boat jumps quickly to plane and runs with the bow high... Me 240, buddy 200, We switched positions running the boat with me up front and him driving...same speeds, same hole shot, same quick to plane... Let's hear the thoughts............. Thanks in advance.. |
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| Author: | DENNYEDWARDS [ Thu Sep 24, 2009 10:10 am ] |
| Post subject: | Re: Help me understand cav plate adjustments.... |
Try adding trim tabs to sides of skeg ahead of prop and put a20 degree angle down on them, we used 2.5x1/8 angle iron to make ours. They worked better than adding angled plate to rear of cav. plate. They look alot like GDs' rockguards in shape. We bolted them on until we found correct angle then welded them in place. Serves a dual purpose in protecting prop also. |
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| Author: | Wingman [ Thu Sep 24, 2009 11:04 am ] |
| Post subject: | Re: Help me understand cav plate adjustments.... |
Normally - the prop depth is where ever the cavitation plate is aligned to be level with the water surface - usually a tall model motor on a short transom model boat wants to run too deep. The prop should track at what ever depth the cav plate is parallel to the boat bottom unless some other force is exerted on it by the trailing edge or prop or driver. But bending the last inch or trailing edge of the cav plate is your fine tuning. Also a very worn prop or a rebuild with too much cup added has more "lift" than a new or good prop and will want to pop out on you. So start with tweaking the cav plate trailing edge - possible try a new or good prop if you can too. |
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| Author: | cbrdux [ Thu Sep 24, 2009 11:37 am ] |
| Post subject: | Re: Help me understand cav plate adjustments.... |
I should have mentioned that I have a new prop on the motor. My biggest concern here is having to run the motor while hunched over...I feel like a damn orangutan, not to mention a pain in the azzzz,or should I say lower back.... I'm beginning to wonder if I should build the transom up to 21" in order to accomodate the motor... |
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| Author: | hatchie rat [ Thu Sep 24, 2009 12:20 pm ] |
| Post subject: | Re: Help me understand cav plate adjustments.... |
ive got the easiest fix.....trade with me. i have a tall transom with a short transom motor. just opposite of all of you problems. its a 20hp |
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